The 2000 field season represented the fourteenth year of monitoring several species of Botrychium populations in Minnesota, Iowa, Oregon, and Alaska. A total of 37 plots have been monitored annually including over 2600 individual tagged plants. Populations fluctuate independently within and between plots as well as between years and between plots at different sites. These differences reflect microsite differences such as soil moisture, herbivory, or mycorrhizae. Fire, herbivory, herbicide and timber harvest have an immediate impact on the above-ground sporophytes. The long-term effect of these factors on below-ground structures (gametophytes and juvenile sporophytes) appears to be buffered by the large bank of underground structures. Monitoring reveals populations are fairly resilient and rebound following perturbations though it may take several years. Using what we know about the species biology we can model population responses to natural and man-made perturbations. The model resulting from this analysis predicts greater stability of populations than might be concluded from monitoring above-ground plants. This is a consequence of having a large proportion of the population existing in underground stages. Even catastrophic elimination of all the underground gametophyte and sporophyte stages does not inevitably lead to population extinction because of the importance of the spore bank. Despite highly variable above-ground population fluctuations, below-ground stages provide Botrychium populations with a high degree of buffering against local extinction.

Key words: Botrychium, conservation biology, ecology, population dynamics, population viability analysis, stage-based modeling